Are there other WA server maybe with more players?
If yes, how can i connect?

There are a few other servers, but none of them nearly as active as the official Yorkshire one is. They mostly come to life when the official one isn't working. WA's WormNet is the most active community by far.

If you for some reason still wish to use them, CyberShadow made a lovely ServerList.html that lets you connect to any [known] servers active at a given time.

Here's link: http://maplecenter.net/wormnet/